Johnson has been heavily criticised for a number of disappointing performances since taking over from Brian Ashton two years ago as England have failed to progress as quickly as their supporters would have hoped.
The first man to be named skipper of more than Lions party came under increasing far last week after England were beaten 27-17 by Australia in Perth.
But scowls turned to smiles on Saturday as his side recorded a shock 21-20 win over the Wallabies in Sydney to claim their first success over a southern hemisphere side during Johnson's tenure.
"I never came close to thinking about packing it in. Not seriously. Never. When you're being criticised, you just get on with it and get through it," Johnson told BBC Radio Five Live.
"You judge yourself and I'm my harshest critic. My coaches will tell me if I'm doing things wrong and that's the way it should work.
"I have said all week I don't worry about my record or my job, I worry about this team getting better. We showed we can play. We knew we could, we just had to go and do it."
With the World Cup taking place in New Zealand next year, Johnson is hopeful that Saturday's victory can provide the necessary springboard for global success.
And with young, inexperienced players like Chris Ashton, Ben Foden and Ben Youngs starring at the weekend, Johnson believes hard work and self belief could make England genuine contenders in 2011.
"What it will do is give the guys a belief that they can win Test matches down here," added Johnson.
"What we need to do whatever happens in the next few days is to go away from here and understand how we can get better with the World Cup just 15 months away.
"The players have to have the hunger and be self-critical. We have still got to be better and more consistent but we have won the Test match.
"A lot of things we didn't do well last week we improved on. Defensively we were sharper and we took our tries early on.
"There has been a lot of negativity around them at times in terms of their ability. They have been mentally tough to come through that and play well.
"We had a chat to the players in the week about what happens at the end of the tour.
"The less experienced players need to understand they need to get better and the players need to understand where to improve.
"The team improved from last week and plenty of young players will be better for the experience of the tour and the victory and the defeats, and coming here to play very good teams.
"Ben Youngs is a good example. He played very well. He is very level-headed. Hopefully he will be thinking 'if I work harder I can be better and we can have days like this again'."